Lignite is a fossil fuel which is derivative of fossilized vegetation which was lied down in the carboniferous period for millions of years ago. Over the ages, the vegetation underwent compaction and heating. Brown lignite is an intermediary product of this decomposition before becoming black coal.
As such, lignite is considered to be a low calorific value fuel. However, because of its vegetative origin this material is very rich and beneficial to plants today. It will be therefore, more beneficial to use the lignite
Normally, lignite type materials are used by reacting with alkali with or without heating prior to addition of alkali (U.S. Pat. Nos. 7,198,805, 5,248,814, 5,688,999, 6,695,892).
Fulvic acids are known to haven many useful properties in the field of medicine. Humic acids and fulvic acids which are considered to be very important for plant health can be derived from lignite and present research work is aimed to produce plant nutrition product from lignite. Although some attempts were done in this direction but cost effective and integrated processes for effective conversion of lignite to utilizable plant nutrition products was not done.
Fishcer et al., U.S. Pat. No. 6,695,892 describes a process for production of organic fertilizer by heating and ammoniating treatment of lignite. This described procedure involves heating and treatment with aqueous ammonical medium.
William Alexander [U.S. Pat. Nos. 5,034,045 and 5,026,416] describes water-soluble alkali metal salt of humic acid (for example, liquid potassium humate salt) which can be used in itself to increase agricultural and horticultural crop yield. Further, the aforesaid document states as follows:
“In accordance with an important feature of the present invention, an alkali metal humate salt solution made according to the method of Example 1 can be mixed with a plant nutrient component, including such plant nutrients as nitrogen and/or phosphorous and/or potassium, to improve the yield of agricultural and horticultural crops.”
In order to derive the water soluble alkali metal humate salt solution, the document teaches dispersing ground leonardite in a solution comprising water, potassium hydroxide and aqueous hydrogen peroxide. More particularly, Alexander describes the treating of the alkali metal with leonardite. The derivative of the invention primarily derived by reacting with potassium hydroxide with small amount of addition of hydrogen peroxide in alkaline conditions, so that as explained in these patents to achieve the full advantage of the present condition. According to Alexander, when the humic acid bearing leonardite ore is treated with alkali hydroxide, oxidized sites of humic acid are saturated with readily ion-exchangeable non volatile alkali metal ions, such as potassium ions. Thus, it can be noticed that the product of Alexander is primarily derived by reacting with potassium hydroxide. The reaction condition has been maintained as alkaline so as to enable derivation of an alkali metal salt mainly aiming for cation exchange capacity.
Although there are attempts to produce lower molecular weight compounds from leonardite by using microbial conversion process [U.S. Pat. No. 5,084,160] using Coriolus versicolor and digesting with other microorganisms [wo20006000073] these inventions are costly methods to produce in ton scale and are not much practical to use for agricultural and other purposes.
Thus, there is a need to produce lignite based plant nutrition product with efficiency and economics which is different from the previous cited documents. Also, there exists a need to effectively convert non-nutritionally active constituents present in lignite to more active form thus enabling large scale production of lignite based fertilizers so that these lignite based fertilizers can act as a viable solution to fill the gaps of the present fertilization practices with better integration and sustainability.